In Albania, ultramafic outcrops cover 11% of the surface and have the potential to support nickel phytomining. In a large-scale in-situ experiment on an ultramafic Vertisols in Pojskë we are studying the influence of agronomical practices on Ni phytoextraction yield of Odontarrhena chalcidica (syn. Alyssum murale). Three cropping systems were compared in three plots in 2016–2017; POJ-1 Plot (0.3 ha) was established with plants that had germinated spontaneously without any treatments; POJ-2 plot (0.3 ha) was covered by plants that had germinated spontaneously and was treated with mineral fertilizer (N50P50K50 kg ha⁻¹); and POJ-3 Plot (400 m²) was divided in four sub plots, where O. chalcidica was planted at a density of 4 plants m⁻² on which, we neither applied fertilizer, nor NPK fertilizer (N65P65K65), pig (FPM; N260:P105:K260 + 15 kg ha⁻¹N, P, K) or chicken manure (FCHM; N260:P390:K260 +15 kg ha⁻¹ N, P, K. Irrigation and mechanical control of weeds was done on POJ-3. After 8 months, shoot Ni concentration, biomass, and Ni yields were higher in O. chalcidica treated with manure and the cost of biomass production was smaller. Nickel yield was more promising (145 kg ha⁻¹) than in previous field trials. This study highlights that, using manure, the Ni yield increases Ni phytomining net values, thus agromining can become an economically justifiable agricultural cropping system.

Cities are producers of high quantities of secondary liquid and solid streams that are still poorly utilized within urban systems. In order to tackle this issue, there has been an ever-growing push for more efficient resource management and waste prevention in urban areas, following the concept of a circular economy. This review paper provides a characterization of urban solid and liquid resource flows (including water, nutrients, metals, potential energy, and organics), which pass through selected nature-based solutions (NBS) and supporting units (SU), expanding on that characterization through the study of existing cases. In particular, this paper presents the currently implemented NBS units for resource recovery, the applicable solid and liquid urban waste streams and the SU dedicated to increasing the quality and minimizing hazards of specific streams at the source level (e.g., concentrated fertilizers, disinfected recovered products). The recovery efficiency of systems, where NBS and SU are combined, operated at a micro- or meso-scale and applied at technology readiness levels higher than 5, is reviewed. The importance of collection and transport infrastructure, treatment and recovery technology, and (urban) agricultural or urban green reuse on the quantity and quality of input and output materials are discussed, also regarding the current main circularity and application challenges.

Orobanche nowackiana Markgr. is the only parasitic flowering plant in Europe which is an obligate serpentinophyte. This plant parasitizes the Ni hyperaccumulator Alyssum murale Waldst. & Kit. which grows in many areas including serpentine slopes of Mt. Komjan (Albania). The aims of the study were to investigate this host/parasite relationship from a biogeochemical point of view in order to evaluate: (1) the metal accumulation in different parts of the parasite and host plants and (2) the effect of Orobanche infection on host growth. Soil and plant samples of A. murale and O. nowackiana were analyzed for elemental concentrations after acid digestion using inductively coupled plasma atomic emission spectrometry (Ca, Mg, Fe, Ni, Cr, Co, Zn, Cu, Mn, Na, Al), colorimetry (for N and P), and flame photometry (for K). Individuals of A. murale, both infected and healthy, showed slight differences in their composition of essential elements (N, P, K) and of some micronutrients. The parasite had higher P, K, Na, and lower N, Ca, Mg, Ni, Zn, Co, Mn and Al concentrations than the host. Orobanche nowackiana is a Ni accumulator with 299 mg kg ⁻¹ in the leaves. Hyperaccumulation of Ni by A. murale did not prevent attack by O. nowackiana . After infection there was a decline in Ni concentration and the dry weight of all organs of the host, thus reducing the biomass yield and consequently Ni phytoextraction yield of A. murale . This infection could be a potential threat to the use of A. murale for Ni agromining.